The Hound, Lost Lands Alpha

Double strike, hexproof from green and white.
Cohort—{t}, Tap an untapped Ally you control:
The Hound deals damage equal to its power to
any target.
Whenever The Hound deals 6 or more
damage to a player, it deals that much damage
plus X, where X is equal to the number of
tapped Ally creatures you control.